The present invention relates to a method for the treatment of waste water containing organic pollutants. More particularly, this invention relates to a method for efficient removal of organic pollutants from various colored waster waters such as pulping waste water, water containing natural humic substances and dyeing waste water.
The colored waste waters as mentioned above contain organic pollutants which are possible sources for environmental pollution. Prior to release of these waste waters into rivers and other natural bodies of water, therefore, the organic pollutants must be thoroughly removed therefrom. The pulping waste water, for example, contains lignosulfonates and hemicelluloses in high percentages and, owing to their presence, is seriously impaired in color and shows notably high values of COD and BOD. For tolerable release of this waste water into a river, it is required to be deprived of lignosulfonates and hemicelluloses.
Various methods have heretofore been proposed for the detoxifying treatment of such a waste water. Of the various methods, comparatively effective are the massive lime method which uses calcium oxide as the adsorbent and the coagulation-sedimentation method which uses inorganic coagulants such as aluminum salts, iron salts and magnesium salts. Particularly, the massive lime method (for example, U.S. Pat. No. 3,639,206) has been recognized to provide an advantageous treatment for a specific type of pulping waste water. In its present state, however, this method does not provide satisfactory effects on all sorts of waste waters containing organic pollutants and it has room yet to be improved in terms of capacity for removal of pollutants, capacity for sedimentation of formed flocks, capacity for dehydration of formed slurry, capacity for treatment of formed sludge, etc.
An object of the present invention is to provide a method for efficient, substantially complete removal of coloring organic pollutants which are contained in waste waters which are rich in organic pollutants of any type such as pulping waste water, water containing natural humic substances, dyeing waste water, etc.